As electronic devices have increased in operational functionality and complexity, the cost and difficulties with manufacturing the electronic devices has also increased. In particular, the processing of semiconductor wafers to form components for the electronic devices has become increasingly complex. For example, to shrink the size of an electronic device, the components on the semiconductor wafer must be smaller and the components on the semiconductor wafer must be packed closer together to increase the density of the components. In addition to manufacturing challenges for making smaller components, the components are typically more complex and require many processing steps to form the components on the semiconductor substrate. Of the processing steps, patterning steps are often the most expensive to perform because each patterning step may require a different mask. Masks are pieces of glass that contain patterns that are copied repeatedly onto each semiconductor substrate to form the components. Masks have a limited lifetime and are expensive to create.
As one example, amplifiers are used in many electronic devices. In particular, cellular phones and audio players use amplifiers to produce signals for driving speakers in the devices or headphones connected to the devices. Amplifiers may include resistor and capacitor components that are difficult to form on a semiconductor substrate. Conventionally, manufacturing resistors, capacitors, and other components for an amplifier on the semiconductor substrate requires patterning using two, three, or more masks. Each mask adds complexity and cost to the manufacturing process.
Further, one or more metal layers of the resistor, capacitor, or other components are patterned with a dry or wet etch process. The wet or dry etch of the metal layer may create undesirable effects due to the difficulty of etching metal layers. FIG. 1 shows certain problems encountered during a conventional dry etch process of metal layers. A structure 100 on a semiconductor substrate (not shown) may include a nitride layer 102, a dielectric layer 104, and a conducting layer 106. A hard mask layer 108 may be deposited and patterned with a mask to form opening 110, which will be transferred to the conducting layer 106 through a dry etch. During the dry etch process, ions from a plasma bombard the conducting layer 106 and cause physical removal of atoms of the conducting layer 106. This patterning may form a portion of a resistor or capacitor for an amplifier in the conducting layer 106. During the dry etch process, undesirable effects may occur that negatively impact the structure 100. For example, the opening 110 may not transfer directly into the conducting layer 106. Instead, an angled sidewall 112 may change the shape of the feature of opening 110 in the conducting layer 106. As another example, material etched from the conducting layer 106 may redeposit material 114 onto the dielectric layer 104 during the plasma etch operation. The conducting materials redeposited 114 onto the dielectric layer 104 reduce the dielectric strength of the dielectric layer 104 and reduce the reliability of components formed with the dielectric layer 104. As a further example, the dry etch may undercut a void 116 in the dielectric layer 104. Each of these examples illustrate that the dry etch may not transfer the pattern of opening 110 into the underlying structure 100 with high fidelity. The problems may be further enhanced when the conducting layer 106 is a material that is difficult to etch, such as such as tantalum, tantalum nitride, Titanium, Titanium nitride, Silicon Chromium.
Shortcomings mentioned here are only representative and are included simply to highlight that a need exists for improved electrical components, particularly for amplifiers in consumer-level devices. Embodiments described here address certain shortcomings but not necessarily each and every one described here or known in the art.